Camel Aslf Diarrhea Whith Emphasis in Rotavirus Inffction

The role of rotavirus in camel calf diarrhea in four different areas (River Nile,
Gedarif, Sennar and Blue Nile and Kordofan States) in Sudan was studied. Data about the
epidemiology of camel calf diarrhea its treatment regimen adopted by the owners was
collected and analyzed. The detection of rotavirus antibodies using ELISA and antigen
using five different techniques was applied. Characterization and isolation in tissue
culture of rotavirus from fecal samples was adopted. A total of 383 camel herds were
investigated about the incidence of camel calf diarrhea during wet and dry seasons over
the three years period of study (2000-2002) in the different four areas focused.
The overall morbidity rate of camel calf diarrhea in the four areas of study was
83% while mortality and case fatality rates were 39.9% and 43.3%, respectively. The
morbidity, mortality and case fatality rates of camel calf diarrhea were found to be almost
the same in the four areas focused during wet and dry seasons with slight increase during
wet season. With regards to different treatment regimens adopted to diarrheic camel
calves by the owners, 38.2% were left without treatment, 56.9% had received tetracycline
while other drugs (Diaclean, sulpha, pamizole, traditional drugs, penicillin, antibiotic plus
glucose and flagyle) constituted a very minor percentages.
A serological survey was conducted using group A rotavirus antibody detection
ELISA on 530 camel sera. The overall percentage of positive samples was 48.1%.
Seropositivity was detected in all areas o f study with slightly higher percentage in
Sennar and Blue Nile States. The overall percentage of high antibody titer (4+) was
31.4% and 3+ was 22%. Most of the seropositive samples were at 18-36 month of age
and adult camels with slightly higher percentage in males than females (56.5% males and
43.5% females). A correlation was found between the seropositivity and the clinical
status of diarrhea. The highest percentage of seropositivity was found in healthy camel
calves (69.7%).
A total of 332 fecal samples were examined for group A rotavirus antigen using
ELISA and some of the samples had been examined also by latex agglutination (LA),
immunochromatographic test (IC), polyacrylamide gel electrophoresis (PAGE), electron
microscopy (EM) and ELISA for group C rotavirus antigen. Rotavirus antigen was
detected in 22.6% of samples. Group A rotavirus was detected in 20.2% (13.9% using
ELISA and 6.3% using IC test) while group C rotavirus was detected in 2.4%. Group A
and C rotavirus were detected in all areas of study. No coronavirus antigen was detected
in 302 fecal samples tested.
A comparison was made between the different techniques used for rotavirus
antigen detection. Out of 46 ELISA positive samples, 17 positive, 12 doubtful, 9 negative
and 8 were not tested by IC while 8 positive, 1 doubtful, 17 negative 20 were not tested
by LA, 11 positive 34 negative and 1 not tested by PAGE. Six positive, 16 negative and
24 were not tested by EM. Out of 281 ELISA negative samples, 20 IC and 1 LA positive
results were obtained. The result revealed a higher sensitivity of ELISA and IC over the
other tests. All PAGE positive samples showed the characteristic group A rotavirus short
electropherotype.
Group A rotavirus VP6 subgroup specificity was detected in 31 out of 42 tested
samples in which subgroup II was predominated (54.8%). Reverse transcription
polymerase chain reaction (RT/PCR) was applied on 10 ELISA positive samples for
detection of group A rotavirus RNA as well as VP4 and VP7 genotyping. Seven samples
were positive using RT/PCR from which 5 could be genotyped for VP4 and VP7 genes.
Two samples were G11, 2 G3 and 1 was G6 while 4 samples were P[11] and 1 was P[4].
Trials for rotavirus isolation in tissue culture were applied on 29 samples (17
group A, 8 group C and 4 group A and C ELISA positive samples). A progressive
rotavirus characteristic cytopathic effect (CPE) was seen on 26 of tested samples (15
group A, 8 group C and 3 group A and C). CPE detected for both groups (A and C) were
round cells, granulated, vacuolated, elongated refractile and giant cells. Rotavirus was
identified in tissue culture harvest using ELISA and IC for group A and EM for both
group A and C rotaviruses.
This is the first report for the detection of camel group A rotavirus antigen in
different areas of Sudan, the detection of group C rotavirus antigen in camels, the
detection of group A rotavirus VP6 subgroup specificity. The results of this study
revealed also the first report of camel group A rotavirus genotyping and isolation of
group A and C rotavirus in tissue culture.